This invention relates to systems and methods for processing blood, e.g., for filtration, pheresis, or other diagnostic or therapeutic purposes.
There are many types of continuous and intermittent blood processing systems, each providing different therapeutic effects and demanding different processing criteria.
For example, hemofiltration emulates normal kidney activities for an individual whose renal function is impaired or lacking. During hemofiltration, blood from the individual is conveyed in an extracorporeal path along a semipermeable membrane, across which a pressure difference (called transmembrane pressure) exists. The pores of the membrane have a molecular weight cut-off that can thereby pass liquid and uremic toxins carried in blood. However, the membrane pores can not pass formed cellular blood elements and plasma proteins. These components are retained and returned to the individual with the toxin-depleted blood. Membranes indicated for hemofiltration are commercially available and can be acquired from, e.g., Asahi Medical Co. (Oita, Japan).
After hemofiltration, fresh physiologic fluid is supplied to toxin-depleted blood. This fluid, called replacement fluid, is buffered either with bicarbonate, lactate, or acetate. The replacement fluid restores, at least partially, a normal physiologic fluid and electrolytic balance to the blood. Usually, an ultrafiltration function is also performed during hemofiltration, by which liquid is replaced in an amount slightly less than that removed. Ultrafiltration decreases the overall fluid level of the individual, which typically increases, in the absence of ultrafiltration, due to normal fluid intake between treatment sessions.
Following hemofiltration, fluid balancing, and ultrafiltration, the blood is returned to the individual.
One aspect of the invention provides a fluid processing system comprising an extracorporeal circuit for circulating a fluid from an individual through a filter to remove waste and to return fluid to the individual after removal of waste. A first portion of the extracorporeal circuit is integrated, at least in part, within a first panel. A second portion of the extracorporeal circuit is integrated, at least in part, within a second panel. The system further includes a fluid processing cartridge, which orients the first and second panels for mounting as an integrated unit on a fluid processing machine and for removal as an integrated unit from the fluid processing machine.
In one embodiment, the first portion of the extracoporeal circuit handles waste fluid, and the second portion of the extracoporeal circuit handles replacement fluid for return to the individual.
In one embodiment, the first and second portions of the extracorporeal circuit include in-line chambers that volumetrically balance waste fluid removed from the individual and waste replacement fluid returned to the individual. The in-line chambers can occupy a fixed volume cavity on the fluid processing machine, whereby the in-line chambers possess a volume defined by the fixed volume cavity on the machine.
In one embodiment, at least one of the first and second panels includes an operative region that flexes in response to an external force applied by the fluid processing machine. The operative region can comprise, e.g., an in-line clamping region that flexes to occlude fluid flow, or an in-line pump tube that flexes in response to peristaltic force to pump fluid, or an operative region that permits sensing of a flow condition by a sensor on the fluid processing machine.
In one embodiment, the fluid processing cartridge includes a tray containing the first and second panels, which are oriented within the tray in an overlaying relationship.
Another aspect of the invention provides a blood processing system. The system comprises an extracoporeal fluid circuit. The circuit includes a first flexible panel having a pattern of seals defining a first flow path that forms a part of the extracorporeal fluid circuit. The circuit also includes a second flexible panel having a pattern of seals defining a second flow path that forms another part of the extracorporeal fluid circuit. A fluid processing cartridge retains the first and second flexible panels in an overlaying relationship. The system further includes a fluid processing device including a chassis to removably mount the fluid processing cartridge with the first flexible panel oriented adjacent to the chassis. The fluid processing device includes an actuator on the chassis operating to apply force through the first flexible panel to a region of the second flexible panel to either pump fluid in the second flow path or occlude flow in the second flow path.
The actuator can comprise, e.g. a pump element to apply a peristaltic force to the region of the second flexible panel through the first flexible panel, or an in-line pump tube to which the peristaltic force is applied, or a clamp element to apply an occlusion force to the region of the second flexible panel through the first flexible panel.
In one embodiment, a sensor on the chassis senses a flow condition in the second flow path through the first and second flexible panels.
In one embodiment, the fluid processing cartridge includes a tray movable into and out of association with the chassis. In one arrangement, the tray includes a cut-out exposing a region of the first flexible panel to the actuator.
Another aspect of the invention provides a hemofiltration machine. The machine includes a chassis and an operating element on the chassis comprising at least one of a peristaltic pump, a clamp, and a sensor. A door is movable with respect to the chassis between a first position enabling mounting of a fluid processing cartridge on the chassis and a second position holding the fluid processing cartridge on the chassis in a predetermined orientation with the operating element.
In one embodiment, the door moves in a path toward and away from the chassis.
In one embodiment, a depression on the chassis defines a space of known volume to accommodate a fluid balancing chamber carried in the fluid processing cartridge.
In one embodiment, the door includes at least one pump race for registry with a pump region carried in the fluid processing cartridge.
Another aspect of the invention provides a fluid processing method. The method establishes an extracoporeal fluid circuit that communicates with a filter. The method defines within a first panel a first flow path that forms a part of the extracorporeal fluid circuit, while defining within a second panel a second flow path that forms another part of the extracorporeal fluid circuit. The method orients the first and second panels in a fluid processing cartridge for mounting as an integrated unit on a fluid processing machine and for removal as an integrated unit from the fluid processing machine.
In one embodiment, the method orients the first and second panels in an overlaying relationship.
Other features and advantages of the inventions are set forth in the following specification and attached drawings.